The prior art is already aware of many different arrangements for apparatus and method for handling sheets of paper or the like, and this prior art includes sheeters, stackers, collators, signature gatherers and feeders, and the like. In this prior art apparatus and method, sheets are handled by either taking them from an incoming stream and forming them into a stack or by taking a stack and distributing or separating the sheets from the stack, all for the general and well known purposes of handling sheets in the printing and magazine and bookbinding industry. Where sheets are handled from an original stream relation and formed into a stack, these sheets may be in a shingled stream form from which they are stripped off and formed into the stack, and one such example is seen in U.S. Pat. No. 3,653,656. Also, a prior art example of mechanism for taking sheets from a stack and into an individual position is shown in U.S. Pat. No. 2,903,260.
In prior art examples of handling sheets individually on rotating drums or the like, for the purpose of transferring the sheets and to either move them into a stream or stack position or move them from a stream or stack position, the aforesaid two U.S. patents show drums with grippers for individually moving the sheets in the rotation of the drum, and also U.S. Pat. Nos. 1,624,985 and 2,413,358 and 3,841,622 are examples of transfer drums or the like with sheet gripper members thereon.
The present invention differs from the prior art in that it provides apparatus and method for handling folded sheets which are spaced apart on a conveyor or the like and which are moved to two oppositely rotated spider or like members which have engagers for alternately receiving the sheets and moving them into a stack so that the fold can be on opposite sides of the stack for adjacent ones of the sheets in the stack. As such, the present invention provides a compensating type of stacker which takes into account the location and effect of a folded sheet or signature in a stack. Thus the present invention provides apparatus and method for stacking folded signatures in alternate directions to form a level or truly vertical stack which is not tipped because of the folds which might otherwise be located completely on one side of the stack to create the tipped stack.
Further, the present invention provides apparatus and method which rapidly and accurately handles the folded sheets or signatures moved on a conveyor to the stack location, and it completely automates the process and the operator need not handle the sheets from the time that they are in a spaced-apart relation on an incoming conveyor and to the time that they are placed in a straight stack and moved away from the location of forming the stack. Additionally, the present invention provides the apparatus and method for accurately counting the number of sheets or signatures in each stack, and the invention automatically accomplishes the accurate counting and moves the counted stacks to one side when the stack is accurately completed, as mentioned. Still further, the present invention provides apparatus and method which accomplishes the aforementioned objectives and which does so without pinching, piercing, or otherwise detrimentally engaging or gripping the folded sheets or signatures when they are placed into the stack. That is, the sheets are not physically distorted or damaged, and the invention handles the sheets without any damage thereto and in fact the apparatus improves the fold characteristic of the sheets in the process of forming them into a stack.
Still further, the present invention provides apparatus and method for handling finished magazines, that is a number of sheets in a folded relationship, and the magazines are inherently thick and therefore the present invention provides the manner for handling the magazines which are flowing directly from a binder, and the magazines need not be physically gripped, pierced, or otherwise held or engaged by the apparatus of this invention which receives and deposits the magazines into the compensated stack mentioned but does so without compressing, piercing, or otherwise damaging or marking the magazines.
As further background, the prior art present day manner of stacking magazines or books or the like is to collect a number of the magazines or the books or the like with the folds on only one side of the stack, and then another number of the magazines or the books is collected with the folds placed on the other side of the stack, so that eventually the stack can be level but the two groups of sheets must be separately collected and separately positioned opposite each other for ultimately forming a somewhat level or straight stack of sheets. The present invention avoids the aforementioned concerns and involvement and the resulting inferior stack, and the present invention forms a truly compensated stack with the folds of the magazines or books being alternately disposed on opposite sides of the stack to form a straight and balanced stack. The prior art is already aware of arrangements for counting sheets which are formed into a stack, and one such example is found in U.S. Pat. No. 3,969,993, and the present invention includes arrangements for counting the folded books or magazines and to form the counted compensated stack in an accurate number of folded products and to then move that counted stack away from the location of its formation.
Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings.